Lysine isolation

Aeromonas proteolytica aminopeptidase [a-Aminoacylpeptide hydrolase (Aeromonas proteolytica)] (3.4.11.10) is produced. [A zinc enzyme. Acts most rapidily on L-leucylpeptides, amide and B-naphthylamide. Does not cleave Glu-and Asp-bonds. Similar aminopeptidases were isolated from E, coli and Staphylococcus thermophilus. ] Thermophilic aminopeptidase [a-Aminoacylpeptide hydrolase] (3.4.11.12) is produced. [Metalloen-zymes of high temperature stability and of broad specificity, releasing all N-terminal amino acids, including arginine and lysine. Isolated from Bacillus St ear othermophilus, Talaromyces duponti, Mucor. ]... 

Neither the d- nor L-amino acid oxidase attack free lysine, but they can do so when the e-amino group is acetylated. It has been observed that the D N ratio of lysine isolated from the tissues was nearly the same as that of the labeled lysine fed, which shows that the a-hydrogen atom of lysine is not labile and that this amino acid cannot participate in the transaminase system. From the above it is evident that the catabolism of lysine is not initiated by a reaction which gives rise to the corresponding a-keto acid. This may be due to the fact that the e-amino group prevents lysine from being a suitable substrate for the enzymes that react with the a-amino group. 

A speculative scheme for the biosynthesis of lysine has been proposed by Strassman and Weinhouse on the basis of the distribution of the label in the lysine isolated from the yeast, Torulopsis utilis, grown on methyl-and carboxyl-labeled acetate. 

H02CC(H)(NH2)(CH2)3C(H)(NH2)C02H. M.p. at least 305"C. The o, l and meso forms are all isolated from hydrolysates of bacterial proteins. It is an intermediate in the biosynthesis of lysine in many bacteria. 

Kikuchi Y, H Kojima, T Tanaka, Y Takatsuka, Y Kamio (1997) Characterization of a second lysine decarboxylase isolated from Escherichia coli. J Bacterial 179 4486-4492. 

A group at the Bach Institute in Moscow was able to isolate a flavine pigment (an isoalloxacine derivative) from the polymer obtained by heating a mixture of three amino acids (glutamic acid glycine lysine = 8 3 1) this exhibited photochemical acivity (e.g., redox reactions such as electron transfer to acceptors with lower Eo values) under both aerobic and anaerobic conditions (Kolesnikov and Kritsky, 1999). 

Figure 16.4 Graph depicting the percentage of lysine residues among peptides that bind to the indicated monoclonal antibodies. The peptides were isolated after affinity selection (biopanning) from a phage-displayed combinatorial peptide library. The peptides are grouped as to whether they are susceptible to formalin fixation, resulting in a loss of immunoreactivity.

Carbohydrate derivatives with a spiroisoxazoline moiety, present in psammap-lysins and ceratinamides (metabolites isolated from marine sponges) have been prepared in good yields and excellent regio- and diastereoselectivity by a route involving Wittig olefination and 1,3-dipolar cycloaddition as key steps (477). 

Toray (1) A large Japanese chemicals manufacturer, perhaps best known for its process for synthesizing /-lysine for use as a dietary supplement. The starting material is cyclohexene which is converted in five steps to racemic lysine. An enzymic process isolates the desired optical isomer, the other is recycled. 

By means of a procedure described above, Hanson and Fittkau (HI) isolated seventeen different peptides from normal urine. One of them, not belonging to the main peptide fraction, consisted of glutamic acid, and phenylalanine with alanine as the third not definitely established component. The remaining peptides contained five to ten different amino acid residues and some unidentified ninhydrin-positive constituents. Four amino acids, i.e., glutamic acid, aspartic acid, glycine, and alanine, were found in the majority of the peptides analyzed. Twelve peptides contained lysine and eight valine. Less frequently encountered were serine, threonine, tyrosine, leucine, phenylalanine, proline, hydroxyproline, and a-aminobutyric acid (found only in two cases). The amino acid composi-... 

Alkalization, 19 761-762 Alkaloids, 2 71-113 in coffee, 7 253 economic aspects, 2 107-109 lysine-derived, 2 80-82 major orders bearing, 2 75 miscellaneous types, 2 106-107 nitrogen introduction into terpenoid skeleton, 2 100-105 occurrence, detection, and isolation, 2 75-77... 

Characteristically, legume seeds are rich in protein and contain intermediate to high levels of lysine and threonine which are important in balancing the deficiencies of these essential amino acids in cereal diets. Certain legume proteins, such as soybean, also exhibit strong functional properties, especially water solubility, water and fat binding and emulsification. Thus soybean flours, protein concentrates and isolates have been used widely as nutritional supplements and functional ingredients in foods. 

The literature on concentrated sweet potato protein is sparse. Amino acid patterns for sweet potato protein isolates have been reported by three groups (16, 45, 46). One report showed that when compared to the FAO standard (47), no amino acids were limiting. The other reports showed total sulfur amino acids and lysine to be limiting (Table III). The patterns indicate a nutritionally well balanced protein. The improvement in nutritional quality, when compared to amino acid patterns from whole sweet potato, is due to the fact that whole sweet potatoes contain substantial amounts of NPN, which consists mainly of nonessential amino acids. This effectively dilutes the EAA and lowers the amino acid score. 

The way biotin participates in carbon dioxide fixation was established in the early 1960s. In 1961 Kaziro and Ochoa using propionyl CoA carboxylase provided evidence for 14C02 binding in an enzyme-biotin complex. With excess propionyl CoA the 14C label moved into a stable position in methyl malonyl CoA. In the same year Lynen found biotin itself could act as a C02 acceptor in a fixation reaction catalyzed by B-methylcrotonyl CoA carboxylase. The labile C02 adduct was stabilized by esterification with diazomethane and the dimethyl ester shown to be identical with the chemically synthesized molecule. X-ray analysis of the bis-p-bromanilide confirmed the carbon dioxide had been incorporated into the N opposite to the point of attachment of the side chain. Proteolytic digestion and the isolation of biocytin established the biotin was bound to the e-NH2 of lysine. 

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